Dynatron synchronous detector



Dec. 8, 1925. I

A. w.y HULL DYNATRON sYNcHRoNous DETECTOR origin'al Filed-Nov. 13. .1920

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ALBERT w. HULL, or soHaN-nfo'rADY, NEW-ilona, AssIGNoR' 'ro sananet Emerald COMPANY, A f CORPORATION or NEW Yeux.

DYnA'rnoN sYNoHnonoUs pepperoni Application 1ed`Novemb'er 1,3, 1920,'S'erialp'o. 423,952. Renewed February 3, 1925i.

To all whomz't may concern.'

" Be it known that I, A LER'rfW.

a citizen `of the United States, residing at Schenectady, in the county of Schenectady, 5 'State of New York, have invented certain' new and useful Improvements iniDynatron Synchronous Detectors, of which the-following is a specification.r .I

My presentl invention relates to detectors for kproducing `a desired indication of signaling currents and more .particularly to detectors which are adapted to produce an audible indication of signaling currents of inaudible ,frequency suoli lfor example, as

r high frequencycontinuous waves commonly' employed for radio signaling purposes.

The novelfeatures which I believe .toi be vcharacteristic of my inventionare set forth with particularity in the appended claims,l

s invention itseiii, hoWevergkboth asto its action and mode of operatori, together e scts' and' advantages thereof will Y .nstood by referencel to the `iollowing description taken in` connection. with the accompanying drawingin which Figs. 1 and 2 are diagrammatic representations of two different*circuitA arrangements which lmay be employedzin-'carrying my invention into4 effect.

receiving and detecting radio signals of the continuous wave type. As shown in the drawing this system comprisesv` anfele'c-` tron `discharge device 1, .which .1s pref- Vice compri-ses an evacuated envelope 1 containing a. filamentary cathode 2, an electrode f1- 3, whichl for convenience of" description I call the anode, and a third electrode 4, which surrounds the cathode and anode.. Asource otpotential 5 supplies current to the-anode 2 for 'heating it'to such a temperature that it will emit the desired quantity of elecwith res ect 'to the cathode 2. A third source o `potential 7 is impressed between In Figi 1, I have represented a system forv trons. The source of potential dmaintainsF the anode 3 ata-constant'positive potentialcathode'2 and third electrode 4 for adjust' varyinverselyas the potential which isv applied to the circuity between cathode and third electrode. A magnetizing coil 8, `which is indicated at the right of' the de- In the `operation of. the system signaling* currents received upon the antenna 9 are impressed from the primar 10 of atransformer upon a resonant receiving circuit, which includes the-inductance 11 and coridenser 12. rllhis resonant circuit being included'in the external,circuitbetween cathode 2 and third electrode 4, the potentials impressed thereon from the antenna tend to produce variations in the current between cathode 2 and third electrode 4.52:) In the absence of any controlling means, however,

these current variations will be`;hi.gh frequency variationscorresponding'to the high frequency variations set up in the antenna 'bythefsignaling currents, and willproduce no audible indicati-on in the telephone receiver 13 which is included 4in 'the .circuit between 4cathode and third electrode. When, however,'a magnetizing field is, produced by means of the coil8, the current between cathode and third electrode will be caused to vary in accordance with variations in the magnetic field.` If current'is supplied to the magnetiz'ing coil 8` by means of analternating source 14 having a'Y frequency equal to one-half .that of the frequency of the signals which arereceived the' current between cathode and third electrode'l .will be caused to vary' in. accordance Awith the 'variations supplied by the source 14. The currentowing in the circuit between cathode and third electrode then instead ot being a pure alternating current of the sig naling frequency will have a direct .current v i',

component introduced therein, that is, im-` pulses of one polarity will; be suppressed or greatly diminishedwhile impulses of the opposite polarity will How` between the electrodeswith undiminished or sligthlyA di- `minished amplitude. This direct current will continue as longy as a signall is being.' received and will not' produce any effect I upoiihthe `telephone receiver 13. It would, however, be capable ofv controlling the operation of any indicating device which may be operated by a steady direct current.

i If, on the other hand, the frequency of the source 14C dilfers from one-half that of the signals to be received by an amount within the audible range, the current'in the circuitv between the cathode and third electrode will have introduced therein in addition to the liigh frequency component van alternating current' component whose frequency is determined by the difference in Afrequency between that of the source 14 and half the frel from a direct current source 1G, adjustable resistance l7ribeing included in this circuit for adjusting the strength of the magnetic field to a desired value. In this case the source 1 4 may be of a frequency differingv from the frequency of the signaling current by an amount within the audible range.

`The device lwill preferably be so adjusted 'i that it will have a. sufficient val-ue of nega* tive resistance to compensate for the re sistance losses in the antenna and inthe receiving circuit so thatthe device will act not only as a detector but lalso as an amplifieix In Fig. 2I have shown an arrangement which differs from that of'Figjl in that the-local highfrequency oscillations are produced in the circuit between cathode and j third electrode, andthe signaling' current is utilized to produce a magnetic field in the sired frequency.

device; cathode and third electrode includes induc- -tance 18inparallel with-the capacity 19, this inductance and capacity forming an oscilbe timed to the de-v i coil, meansfor producing locally high frelatory circuit which may Ihe'n the device 1.- is 'adjusted to operate asanegative resistance oscillations will normally be produced in this oscillatory circuit. When the signaling currents to be detected are impressed upon the coil 20, therebyproducing a magnetic field in the device, the amplitude of the high frequency y'oscillations which are produced will be varied in accordance with the variations in this magnetic field.

The operation of the device 1n so far asthe effect upon the current between cathode and third electrode is concerned will be the same as in the case of Fig. 1. If it is` desired to employ a constantmagnetic field in addition to the variable field produced by the signaling currents a source of direct current 21 In this case the circuit betweenaccessi may be supplied'to the inagnctizing coi1`20,

as indicated. In. this case a condenser 22 maybe inserted in the circuit to preventrthe source 21 from being short circuited by the coil Iland a choke coil 23 inserted in series with the battery to prevent the high fre-i quency current from being short circuited through the battery. preferably shunted by means of condenser 24.1501- the purpose of bypassing the high frequencycomponent of the current flowing in the .circuit therein between the cathode and third electrode.

invention with lVhile I `have describedmy particular reference to a system for-receiving -and detecting continuous wave radio signals it isA apparent thatit is not limited in its utility to this particular use, but' that it may be employed for detection of signaling currents of `inaudible frequency trans-` 'Ihe telephones 13 are mittedover wire lines or for the detection oit-signaling curi-ents of a frequency below audibility. lVhile I have indicated, onlyl two circuit arrangements whereby my invention may be carried into effect it will be' obvious to those skilled in the art that many modifications inl the circuit arrangements employed as well as in the particular form of apparatus used may be made without d'eparting from the scopel of my invention as .set forth inthe appended claims. 'f

lVhat I claim as new and desire tosecure by Letters Patent of the .United States, is-:-v j i 1. The combination in a system' for dei tecting high frequencysignaling currents@y of an. electron discharge device having and velectron emitting cathode,. an anode, and a third lelectrode enclosed in an -evacuated envelope, an electric ycircuit between cathode and'third electrode; sources of potential applied vto thc-electrodes ofsaid device insuch a Way that the current in said circuit will increase and decrease inverselyas lthe potential `between .cathode and third electrode, a magnetizing coil -associated'with said device for produciiigia magnetic field in. the space between -cathode and third electrode,' a second circuit associated4 with said ina'gnetizing quency oscillations of a frequency diiferent from that ofthe signaling currents to be dc-` tected, means for supplying the locally pitoduced high frequency oscillations to .one of said circuits, and means for supplying signalingl currents to the other circuit.

24Tlie' method of `operatingl an electron discharge device, having an electron emit-v ting cathodeand a cooperating electrode enclosed in an evacuated receptacle and having an oscillatory circuit associated withsaid izo electrodes, .which consists inproducing a` flow of 'y electrons between said electrodes i angle to the paths'of said electrons, produc'- ing high frequency oscillations in said oscillatory circuit ot a frequency different from Athat ol the signaling currents to be detected, and producing an indication of the resulting current flowing between said electrodes.

3. The method of' operating an electron discharge device, having an `electron emitting cathode and a cooperating electrode enclosed in an evacuated receptacle and-having an oscillatory circuit associated with said electrodes7 which consists in producing a` Y'flow of electrons between said electrodes,- producing by means of a high frequency sig" nalingcurrent to be detected a magnetic t "iield in a direction substantially at a right angle to the paths of said electrons, producing. high frequencyA oscillations in said 4oscillatory circuit and producing an indication ofthe resulting currentiiowing between said electrodes.

4. The method of .operating an electron 'discharge device, having 'an electron emitting cathodeand ac'ooperating electrode en closed in an evacuated .receptacle and having an oscillatory circuit associated' with said electrodes, which consists in producing a flow ot electrons between ysaidrelectrodes, producing by means of a signaling current to be detected a magnetic field in a di- Ircction substantially'at a right angle to the pathsofsaid electrons, producing. oscillations in said oscillatory circuitot a fre' quency dillerent from that of the signaling currents to be detected, and producing an indication of the resulting current flowing between said electrodes. v

5. Thevmethtid of operating an electron discharge device, having an electron emitti ng cathode and a cooperating electrode enclosed in an evacuated receptacle and having an oscillatory circuit associated with" said electrodes, \\'liicli'coiisists in yproducing a flow ot' electrons between said electrodes,v producing by means of a signaling current to bc detected a magnetic. held in a direction substantially ata right angle to the paths of said electrons, producing.oscillations in said I oscillatory circuit and producing an indication of the resulting current flowing between said electrodes.

The combination in a system for detecting high frequency signaling currents of an electron discharge device having an electron' emitting cathode, an anode and a third electrode enclosed in an e 'acuated receptacle, an oscillatory circuit connected between cathode and third electrode, sources of potential apl plied to thc electrodes of said device in such a way that the current between cathode and third electrode will increase and decrease inversely as the potential between cathode and third electrode, said oscillatory circuit being so proportioned. that high frequency oscillations will be produced therein, a magnetizing coil associated with said device` and.

adapted to produce a magnetic fieldinthe coil the high frequency: signalingv currents'` lto be detected, and meansl or'iproducingan indication of the resultant current in the circuit betiveencathode andthird electrode when vthe signaling currents are supplied to the magnetizing coil. y y 7. The combination in'a-systemor detecting` high frequency signaling currents of an.- electron discharge device having an electron emitting cathode, an anode, and a third electrede enclosed in 'ian evacuated. receptacle, an oscillatory .circult connected between cathode and third electrode, lsources ior' po# tential applied to the'electrodesv of said de`` vice. in Such a way that the current between cathode `and third electrode will increase and 'decrease inversely as the potential between cathode and third electrode, said oscilla tory circuit being so proportioned thathigh frequency oscillations will .be produced therein of' a frequency different from that ot the signaling currents to be detected, avv magnetizing coil 'associated with said device and adapted to produce a magnetic lieldin the spaceA between cathode and third electrede, means torsupplying to said magnetizing coil the high frequency signaling .currents to be detected, and means for produc` ing an indication of the resultant current in the circuit between cathode and third elec trede when-the signaling currents are supplied to' the magnetizing coil. S. The. cqmbination inea system for-del.' tecting high frequency signaling currents of an electron discharge device having anelecffl tronemittingicathode, an anode, anda third 105 electrode enclosed in an'evacuated receptacle, an oscillatory circuit connected between cathode a'nd third electrode,4 sources ofpotential applied to the electrodes of said device in such a Way that` the current be'` tween cathode and third electrode will in'-A4 crease and decrease inversely as the potential between* cathode and third electrode, sai-d oscillatory circuit being s o proportioned that oscillations will be produced therein, a magnetizing coil associated with said device and adapted to produce a magnetic tield in the.

Space between cathode and third electrode;v

means for supplying to said magnetizing coil the signaling currents to be detected, and means for producing an indication of theresultant current in the circuit, between cathode and third electrode. when the signaling currents vare supplied to the magnetizing coil. l

9.. The combination in a system for dctect. ing high frequencyy signaling currentsof an electron discharge device having an electron emitting cathode, an anode, 'and a third electrode enclosed in an evacuated receptacle, an

. oscillatory circuit connected between cathode and third electrode, sources of potential applied to the electrodes ot said device in such va way that the current-between cathode andI third electrode will increase and decreaseinvers'ely as the potential between c athcde and third electrode, said oscillatory circuit being so proportioned .that oscillations Will be pro- `currents are supplied to the ducedtherein ot a frequency dierent from that ofthesignaling currents to be detected, a inagnctizing coil'associated with said 'device and adapted to produce a magnetic field circuits associated with said device, one ot said circuits having a negative resistance vincluded therein, a second of said circuits including means for varying the value of thefnegative 4resistance of the first, means for impressing signaling currents upon one y of the circuits associated with said device,

and means for producing local oscillations in another of said circuits of a frequency diering from that ofv tl'iesignaling currents.

11.. The combination. in a system for de4 tecting lhigh frequency signaling currents ofv an electron discharge device having aof an .electron discharge device having a 'plurality 'of electrodes and a plurality of Ycircuits associated With said device,- oiie of said ,circuits having -a negative resistance included therein, a second of said circuits including magnetic meansfor varying the value of the negative'resistance of the first, means for impressing signaling currents up- -on vone of the circuits associated With said device, and ,means for producing local os-` cillations in anotherof said circuits of a frequency differing from that of the signaling currents.

J 12. The combination in a system for detecting high frequency signaling currents accessi plurality of electrodes and a plurality of circuits associated with said device, one-'of said er circuits which is connected between two of the electrodes of said device having a negative resistance included therein', a second of' said circuits including means'for varying the value of the negative resistance of the first,

means for impressing signaling currents upon one of the circuits associated With said device, and means for producing local oscillations in another of said circuits of a frequency diiferingfrqm that of the signaling currents. y

13. The. combination ina system for de tecting high frequency signaling currents of 'an electron discharge device having a plurality of electrodes enclosed in an evacuated receptacle and a plurality of circuits associated with said device, one of said circuits which is connected between tivo of the electrodes of said device having a negative resistance included therein, a second of said circuits including a inagnetizing coil'surrounding said receptacle for varying the value of the negative resistance of the first, means for impressing signaling currents up- .on one of. the circuits associated with said device, and means for producing local oscillations in another of said circuits of a frequency differing from that of the signaling currents.

14. The combination in asystem forl-defs tecting high frequency signaling currents ofv an electron discharge device having a plurality of electrodes enclosed in an evacuated recepta'cleand fa plurality of circuits associatedwith saiddevice, onel of said circuits 'which is connected between AtWo of the electrodes of said device having a negative resistance included therein, a second of said circuits including a magnetizing coil sur-v roundingv sai-d receptacle for varying the 95 value of the negative resistance of the first,

means for impressing signaling currents up'- nn`the second ot the circ-nits associated with said device and means` for producing local oscillations in the iirst of said circuits ot a frequency differing from that ofthe sig-4 naling currents. v

In Witness whereof, I have'hereun'to set my hand this 12th day of November 1920.

- interina? W. HULL. 

